Java Code to Receive Mail using JavaMailAPI

Introduction:

In the previous article, we have looked at sending mail with Java Mail API.Sending e-mail was relatively simple with only one protocol (SMTP) to handle. But Reception involves two protocols, POP3 and IMAP. POP3 is the older protocol, which offers a single queue of mail messages as a single inbox. IMAP is the more modern protocol, which presents mail messages as entries in a hierarchy of folders, one of which will be an inbox.

Java Mail comes with Provider implementations for POP3 and IMAP, and the secure versions of those as POP3S and IMAPS.

Prerequisites:

JDK 1.5 and Above

Jar: Mail. jar

Steps involved in receive mail:

Step 1: Define the mail properties (i.e.) Define the protocol, mail server by using the properties class.

Step 2: Create the session for read the mail with the properties which we already defined.

Step 3: Create and connect the store for read the mail.

Step 4: Define and open the folder which we need to read. Open the folder in read-only mode.

Step 5: Search the unread contents in the specified folder and stored it into messages array.

Step 6: Display the messages.

Description of classes and methods :

Store:

An abstract class that models a message store and its access protocol, for storing and retrieving messages.

Methods:

connect -> It is used to connect the store with the mail server store.

getFolder-> It is used to define the folder which will be read. Return Folder class.

Folder:

Folder is an abstract class that represents a folder for mail messages. Folders can contain Messages, other Folders

Methods:

open   -> Method for open the foder.We must define the mode of open.

search -> Method for get the messages. Return type: Message[].

fetch  -> Method for Fetch the details which is represented by FetchProfile.

close  -> Method for close the folder.

FetchProfile:

List the Message attributes that it wishes to prefetch from the server for a range of messages.

Method:

add  ->  Method for add the attributes which we wish to prefetch.

Message:

This class models an email message. This is an abstract class. Message implements the Part interface

A Message object obtained from a folder is just a lightweight reference to the actual message.

Methods:

getContent  ->  Method for get the content of the message.

Code:

/*
 *  This is the code for read the unread mails from your mail account.
 *  Requirements:
 *      JDK 1.5 and above
 *      Jar:mail.jar
 *
 */
package com.info.mail;
import java.io.*;
import java.util.*;
import javax.mail.*;
import javax.mail.Flags.Flag;
import javax.mail.search.FlagTerm;

public class MailReader
{
 Folder inbox;

 //Constructor of the calss.
 public MailReader()
 {
 /*  Set the mail properties  */
 Properties props = System.getProperties();
 props.setProperty("mail.store.protocol", "imaps");
 try
 {
 /*  Create the session and get the store for read the mail. */
 Session session = Session.getDefaultInstance(props, null);
 Store store = session.getStore("imaps");
 store.connect("imap.gmail.com","<mail ID> ", "<Password>");

 /*  Mention the folder name which you want to read. */
 inbox = store.getFolder("Inbox");
 System.out.println("No of Unread Messages : " + inbox.getUnreadMessageCount());

 /*Open the inbox using store.*/
 inbox.open(Folder.READ_ONLY);

 /*  Get the messages which is unread in the Inbox*/
 Message messages[] = inbox.search(new FlagTerm(new Flags(Flag.SEEN), false));

 /* Use a suitable FetchProfile    */
 FetchProfile fp = new FetchProfile();
 fp.add(FetchProfile.Item.ENVELOPE);
 fp.add(FetchProfile.Item.CONTENT_INFO);
 inbox.fetch(messages, fp);

 try
 {
 printAllMessages(messages);
 inbox.close(true);
 store.close();
 }
 catch (Exception ex)
 {
 System.out.println("Exception arise at the time of read mail");
 ex.printStackTrace();
 }
 }
 catch (NoSuchProviderException e)
 {
 e.printStackTrace();
 System.exit(1);
 }
 catch (MessagingException e)
 {
 e.printStackTrace();
 System.exit(2);
 }
 }

 public void printAllMessages(Message[] msgs) throws Exception
 {
 for (int i = 0; i < msgs.length; i++)
 {
 System.out.println("MESSAGE #" + (i + 1) + ":");
 printEnvelope(msgs[i]);
 }
 }

 /*  Print the envelope(FromAddress,ReceivedDate,Subject)  */
 public void printEnvelope(Message message) throws Exception
 {
 Address[] a;
 // FROM
 if ((a = message.getFrom()) != null)
 {
 for (int j = 0; j < a.length; j++)
 {
 System.out.println("FROM: " + a[j].toString());
 }
 }
 // TO
 if ((a = message.getRecipients(Message.RecipientType.TO)) != null)
 {
 for (int j = 0; j < a.length; j++)
 {
 System.out.println("TO: " + a[j].toString());
 }
 }
 String subject = message.getSubject();
 Date receivedDate = message.getReceivedDate();
 String content = message.getContent().toString();
 System.out.println("Subject : " + subject);
 System.out.println("Received Date : " + receivedDate.toString());
 System.out.println("Content : " + content);
 getContent(message);
 }

 public void getContent(Message msg)
 {
 try
 {
 String contentType = msg.getContentType();
 System.out.println("Content Type : " + contentType);
 Multipart mp = (Multipart) msg.getContent();
 int count = mp.getCount();
 for (int i = 0; i < count; i++)
 {
 dumpPart(mp.getBodyPart(i));
 }
 }
 catch (Exception ex)
 {
 System.out.println("Exception arise at get Content");
 ex.printStackTrace();
 }
 }

 public void dumpPart(Part p) throws Exception
 {
 // Dump input stream ..
 InputStream is = p.getInputStream();
 // If "is" is not already buffered, wrap a BufferedInputStream
 // around it.
 if (!(is instanceof BufferedInputStream))
 {
 is = new BufferedInputStream(is);
 }
 int c;
 System.out.println("Message : ");
 while ((c = is.read()) != -1)
 {
 System.out.write(c);
 }
 }

 public static void main(String args[])
 {
 new MailReader();
 }
}